Note that both keywords and identifiers are case-insensitive;
identifiers can preserve case by surrounding them with
double-quotes as allowed by SQL92.
PostgresSQL supports the usual SQL types int,
float, real,
smallint, char(N), varchar(N),
date, time, and
timestamp, as well as other types of
general utility and a rich set of geometric types. As we will see
later, Postgres can be customized
with an arbitrary number of user-defined data types. Consequently,
type names are not syntactical keywords, except where required to
support special cases in the SQL92
standard. So far, the PostgresCREATE command looks exactly like the
command used to create a table in a traditional relational system.
However, we will presently see that classes have properties that
are extensions of the relational model.